Extra cals from exercise, but not that hungry!?!?

Ok so typically I am the girl who works out to have a few extra calories. Well lately I have quite a few calories left - say 300 - plus if I work out I have an add'l 300. I enjoy working out but a 5-600 cal deficit makes for a very rough morning (cuz I didn't eat enough the day before). What is going on and how on earth do I fix it? Not working out is just not an option:? TIA